Mechanization may not be able to totally eliminate low-wage and low-skilled jobs that illegal immigrants are eager to fill.

Since the guest worker program for seasonal Mexican workers ended in 1964, the amount of tomatoes machine-harvested for processed foods has quadrupled and the labor employed for such harvesting has dropped by 72%. Similarly, machines have been successfully used to catch, kill, pluck and disembowel chickens in poultry processing plants.

These examples seem to suggest that low-skilled jobs could be easily mechanized and that the availability of cheap illegal immigrant workers would simply postpone the mechanization of labor-intensive jobs.

Mechanization is most successful when the processes are standardized and the end products cannot be easily damaged. Otherwise, mechanization would not be cost-saving. For example, current cantaloupes do not mature uniformly. They cannot be successfully harvested unless the automated machines can tell the ripe and green ones apart. In the case of easily bruised crops such as apples, grapes, romaine lettuce, and salad tomatoes, machines are just not flexible enough to replace manual harvesting.

Crops can, of course, sometimes be bred to mature uniformly and to be less perishable, but not always without sacrificing its taste and texture. Supermarket tomatoes shipped from afar are well known to be less than palatable because they have been bred just to be less perishable.

If mechanization is not the solution, would raising wages attract enough native-born Americans to fill low-skilled jobs? Some jobs may be too tedious and physically demanding to attract native-born American workers even at higher wages. A chicken-processing plant in rural Georgia found it hard to replace the 675 illegal workers it lost after an immigration raid on its 900-member mostly Hispanic work force. Even though the company was able to replace some of the lost workers by raising its starting hourly wages by more than a dollar to $8 - $9, the turnover rate among the newly hired native-born Americans was unacceptably high and their work ethics disappointing compared to the illegal immigrants.

There is also a limit to how much wages can be raised for low-productivity labor intensive jobs. Unless the demand for their direct or indirect services is perfectly inelastic, employers of low-skilled workers may not be able to fully pass the increased labor cost to the final consumers.

If low-skilled jobs cannot be easily mechanized, the demand for low-skilled labor is not inelastic, and legal or illegal immigration is not a viable long-term solution, may be at least some of these jobs could be offshored to low-labor-cost countries. After all, a cheaper imported romaine lettuce tenderly harvested by hand over the Mexican borders should taste just as good as a California-grown lettuce hand-picked by reluctant American workers sold for a higher price at the local supermarket. But the problem of finding high-paying jobs with pleasant working environment for low-skilled native-born American workers still remains.